package com.yhos.platform.oopston.core.mybatis;

import org.apache.commons.lang3.StringUtils;

import java.net.InetAddress;

public class SnowFlake {


    /**
     * 起始的时间戳
     */
    private final static long START_STMP = 1480166465631L;

    /**
     * 每一部分占用的位数
     */
    private final static long SEQUENCE_BIT = 12; //序列号占用的位数
    private final static long MACHINE_BIT = 10;   //机器标识占用的位数  //机器码使用10位
    private final static long DATACENTER_BIT = 0;//数据中心占用的位数   //取消数据中心的占位

    /**
     * 每一部分的最大值
     */
    private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
    private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
    private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);

    /**
     * 每一部分向左的位移
     */
    private final static long MACHINE_LEFT = SEQUENCE_BIT;
    private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
    private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;

    private long datacenterId;  //数据中心
    private long machineId;     //机器标识
    private long sequence = 0L; //序列号
    private long lastStmp = -1L;//上一次时间戳

    private static SnowFlake instance;

    public static SnowFlake getInstance() {
        if (instance == null) {
            return instance = new SnowFlake(0, 0);
        }
        return instance;
    }

	public SnowFlake(long datacenterId, long machineId) {
//		if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
//			throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
//		}
        machineId=getMachineId();
		if (machineId > MAX_MACHINE_NUM || machineId < 0) {
			throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
		}
		this.datacenterId = datacenterId;
		this.machineId = machineId;
	}

    /**
     * 产生下一个ID
     *
     * @return
     */
	public synchronized long nextId() {
		long currStmp = getNewstmp();
		if (currStmp < lastStmp) {
			throw new RuntimeException("Clock moved backwards.  Refusing to generate id");
		}

        if (currStmp == lastStmp) {
            //相同毫秒内，序列号自增
            sequence = (sequence + 1) & MAX_SEQUENCE;
            //同一毫秒的序列数已经达到最大
            if (sequence == 0L) {
                currStmp = getNextMill();
            }
        } else {
            //不同毫秒内，序列号置为0
            sequence = 0L;
        }

        lastStmp = currStmp;

        return (currStmp - START_STMP) << TIMESTMP_LEFT //时间戳部分
//                | datacenterId << DATACENTER_LEFT       //数据中心部分   /取消数据中心部分
                | machineId << MACHINE_LEFT             //机器标识部分
                | sequence;                             //序列号部分
    }

	private long getNextMill() {
		long mill = getNewstmp();
		while (mill <= lastStmp) {
			mill = getNewstmp();
		}
		return mill;
	}

	private long getNewstmp() {
		return System.currentTimeMillis();
	}

    /**
     * Docker 环境下，启动应用是传入DOCKERID参数
     * 非docker环境,参数值是IP地址的第三段+第四段的值，例如：192.168.1.2   计算的值是(1+256)+2=259
     * 是 (1+256)+2=259
     * @return
     */
    private static int getMachineId() {
        try {
            String dockerId=System.getProperty("DOCKERID");
            if(StringUtils.isBlank(dockerId) ) {
                String[] ips = InetAddress.getLocalHost().getHostAddress().split("\\.");
                return Integer.valueOf(ips[2]) + 256 + Integer.valueOf(ips[3]);
            } else {
                return Integer.valueOf(dockerId);
            }
        } catch (Exception e) {
            throw new IllegalArgumentException("get machineId error"+e.toString());
        }
    }

   /* public static void main(String[] args) {
       SnowFlake snowFlake=new SnowFlake(0, 0);
       Map<String, Long> map=new HashMap<String, Long>();
	   Long id = snowFlake.nextId();
	   map.put("key", id); 
       Result result = new Result("0","消息...",map);
       String str = result.retResult(result);
       System.out.println(str);
      for(int i=0; i<10;i++){
    	  Long ids = snowFlake.nextId();
    	  System.out.println(ids);
      }
    }*/
}